Some wear a cheerful expression in affliction (7)
I believe the answer is:
earache
'affliction' is the definition.
'some wear a cheerful expression' is the wordplay.
'some' indicates a hidden word (some parts of the word are used).
'EARACHE' is hidden in the letters of 'wear a cheerful expression'.
'in' acts as a link.
(Other definitions for earache that I've seen before include "Lughole pain" , "result of nagging?" , "stabbing in vestibule?" , "Form of torture" , "otitis" .)